Voltage-flux-characteristics of asymmetric dc SQUIDs

Jochen Müller; Stefan Weiss; Rudolf Gross; Reinhold Kleiner; Dieter Koelle

doi:10.1109/77.919493

Voltage-flux-characteristics of asymmetric dc SQUIDs

Jochen Müller
, Stefan Weiss
, Rudolf Gross
, Reinhold Kleiner
, Dieter Koelle

University of Cologne
RWTH Aachen University
ESAS
Bavarian Academy of Sciences and Humanities (Bayerische Akademie der Wissenschaften)
University of Tübingen

Research output: Contribution to journal › Conference article › peer-review

22 Scopus citations

Abstract

We present a detailed analysis of voltage-flux V(Φ)-characteristics for asymmetric dc SQUIDs with various kinds of asymmetries. For finite asymmetry α_I in the critical currents of the two Josephson junctions, the minima in the V(Φ)-characteristics for bias currents of opposite polarity are shifted along the flux axis by ΔΦ = α_Iβ_L relative to each other; β_L is the screening parameter. This simple relation allows the determination of α_I in our experiments on YBa₂Cu₃O_7-δ dc SQUIDs and comparison with theory. Extensive numerical simulations within a wide range of β_L and noise parameter Γ reveal a systematic dependence of the transfer function V_Φ on α_I and α_R (junction resistance asymmetry). As for the symmetric dc SQUID, V_Φ factorizes into g(Γβ_L)·f(α_I,β_L), where now f also depends on α_I. For β_L≲5 we find mostly a decrease of V_Φ with increasing α_I, which however can only partially account for the frequently observed discrepancy in V_Φ between theory and experiment for high-T_c dc SQUIDs.

Original language	English
Pages (from-to)	912-915
Number of pages	4
Journal	IEEE Transactions on Applied Superconductivity
Volume	11
Issue number	1 I
DOIs	https://doi.org/10.1109/77.919493
State	Published - Mar 2001
Externally published	Yes
Event	2000 Applied Superconductivity Conference - Virginia Beach, VA, United States Duration: 17 Sep 2000 → 22 Sep 2000

Keywords

High-temperature superconductors
SQUIDs
Superconducting devices

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10.1109/77.919493

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title = "Voltage-flux-characteristics of asymmetric dc SQUIDs",

abstract = "We present a detailed analysis of voltage-flux V(Φ)-characteristics for asymmetric dc SQUIDs with various kinds of asymmetries. For finite asymmetry αI in the critical currents of the two Josephson junctions, the minima in the V(Φ)-characteristics for bias currents of opposite polarity are shifted along the flux axis by ΔΦ = αIβL relative to each other; βL is the screening parameter. This simple relation allows the determination of αI in our experiments on YBa2Cu3O7-δ dc SQUIDs and comparison with theory. Extensive numerical simulations within a wide range of βL and noise parameter Γ reveal a systematic dependence of the transfer function VΦ on αI and αR (junction resistance asymmetry). As for the symmetric dc SQUID, VΦ factorizes into g(ΓβL)·f(αI,βL), where now f also depends on αI. For βL≲5 we find mostly a decrease of VΦ with increasing αI, which however can only partially account for the frequently observed discrepancy in VΦ between theory and experiment for high-Tc dc SQUIDs.",

keywords = "High-temperature superconductors, SQUIDs, Superconducting devices",

author = "Jochen M{\"u}ller and Stefan Weiss and Rudolf Gross and Reinhold Kleiner and Dieter Koelle",

year = "2001",

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doi = "10.1109/77.919493",

language = "English",

volume = "11",

pages = "912--915",

journal = "IEEE Transactions on Applied Superconductivity",

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TY - JOUR

T1 - Voltage-flux-characteristics of asymmetric dc SQUIDs

AU - Müller, Jochen

AU - Weiss, Stefan

AU - Gross, Rudolf

AU - Kleiner, Reinhold

AU - Koelle, Dieter

PY - 2001/3

Y1 - 2001/3

N2 - We present a detailed analysis of voltage-flux V(Φ)-characteristics for asymmetric dc SQUIDs with various kinds of asymmetries. For finite asymmetry αI in the critical currents of the two Josephson junctions, the minima in the V(Φ)-characteristics for bias currents of opposite polarity are shifted along the flux axis by ΔΦ = αIβL relative to each other; βL is the screening parameter. This simple relation allows the determination of αI in our experiments on YBa2Cu3O7-δ dc SQUIDs and comparison with theory. Extensive numerical simulations within a wide range of βL and noise parameter Γ reveal a systematic dependence of the transfer function VΦ on αI and αR (junction resistance asymmetry). As for the symmetric dc SQUID, VΦ factorizes into g(ΓβL)·f(αI,βL), where now f also depends on αI. For βL≲5 we find mostly a decrease of VΦ with increasing αI, which however can only partially account for the frequently observed discrepancy in VΦ between theory and experiment for high-Tc dc SQUIDs.

AB - We present a detailed analysis of voltage-flux V(Φ)-characteristics for asymmetric dc SQUIDs with various kinds of asymmetries. For finite asymmetry αI in the critical currents of the two Josephson junctions, the minima in the V(Φ)-characteristics for bias currents of opposite polarity are shifted along the flux axis by ΔΦ = αIβL relative to each other; βL is the screening parameter. This simple relation allows the determination of αI in our experiments on YBa2Cu3O7-δ dc SQUIDs and comparison with theory. Extensive numerical simulations within a wide range of βL and noise parameter Γ reveal a systematic dependence of the transfer function VΦ on αI and αR (junction resistance asymmetry). As for the symmetric dc SQUID, VΦ factorizes into g(ΓβL)·f(αI,βL), where now f also depends on αI. For βL≲5 we find mostly a decrease of VΦ with increasing αI, which however can only partially account for the frequently observed discrepancy in VΦ between theory and experiment for high-Tc dc SQUIDs.

KW - High-temperature superconductors

KW - SQUIDs

KW - Superconducting devices

UR - https://www.scopus.com/pages/publications/0035267907

U2 - 10.1109/77.919493

DO - 10.1109/77.919493

M3 - Conference article

AN - SCOPUS:0035267907

SN - 1051-8223

VL - 11

SP - 912

EP - 915

JO - IEEE Transactions on Applied Superconductivity

JF - IEEE Transactions on Applied Superconductivity

IS - 1 I

T2 - 2000 Applied Superconductivity Conference

Y2 - 17 September 2000 through 22 September 2000

ER -

Voltage-flux-characteristics of asymmetric dc SQUIDs

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Keywords

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